The present invention relates to metal framing construction, and more particularly to a stud for the construction of fire-resistant and seismic resistant shaft walls, i.e., elevator shafts and stairwells, from completely within the shaft cavity.
The present invention discloses a stud for construction of seismic and fire resistant shaft walls, including but not limited to elevator shafts and stair wells, comprising a vertical web with incongruent anterior and posterior flanges depending therefrom, and multiplicity of horizontal slots incorporated in the posterior flange.
This invention is an improvement over the prior art based upon the ease manufacturing the claimed stud and the ease of constructing a shaft wall assembly strictly from inside the shaft cavity, using the method disclosed in U.S. Pat. No. 5,950,385. Construction of seismic resistant and fire resistant shaft wall assemblies using the stud claimed herein and the method disclosed by U.S. Pat. No. 5,950,385 reduces construction costs based upon the ease of assembly and avoiding construction from both inside and outside the shaft cavity.
Conventional sheet metal wall studs are formed of sheet metal bent into a generally xe2x80x9cU-6 shapedxe2x80x9d cross-section in which a relatively broad central stud web is flanked by a pair narrower stud sides of equal length that are bent at right angles to the stud web. The stud web typically has a uniform nominal width of either 4 or 3xc2xd inches, and the sides of the u-shaped stud typically extend a nominal distance of two inches from the stud web. The equal sized flanges require the user to work on both sides of the stud to attach opposing wall board to side of the stud. The opposite flange possessing the same length as the near flange obstructs the users ability to attach the opposite wall board. Consequently, screw drivers or screw guns cannot be inserted into the channel formed between the equal size flanges depending from the stud web to attach the wallboard located on the side opposite from the user without the user being positioned on the same side as the wallboard to complete the installation.
Likewise, the slotted channel claimed in U.S. Pat. No. 5,127,203, issued to Robert Paquette suffers from the same limitation as a conventional sheet metal stud. To construct the wall assembly disclosed in U.S. Pat. No. 5,127,203, the user must work on both sides of the slotted channel to install the studs and wallboard. Again, like the conventional sheet metal wall stud, a screw driver, screw gun or nail gun cannot be inserted into the channel formed between the equal size flanges depending from the web of the slotted track to attach the wallboard located on the side opposite from the user. Consequently, the user must be positioned on the same side as the wall board to be installed to complete the installation of the wallboard.
The invention disclosed in U.S. Pat. No. 4,152,878 is not cost effective to produce because the stud requires bending at least six separate locations as well as additional raw material to create the claimed stud. In comparison, the stud claimed herein requires four folds to form the xe2x80x9cjxe2x80x9d-shaped stud. Thus, less material is required to form the present invention.
U.S. Pat. No. 5,724,784 invented by Robert J. Menchetti, issued on Mar. 10, 1998, discloses a shaft wall supported by a horizontal stud. The Menchetti invention fails to provide a means by which a fire-resistant and seismic resistant shaft wall structure can be constructed. The Menchetti invention claims a means for constructing a static shaft wall which would not survive seismic forces without compromising the integrity of the completed wall structure. Moreover, the Menchetti invention does not claim to create a fire-resistant shaft wall which would satisfy the requirements of existing building codes.
The present invention is an improvement over U.S. Pat. Nos. 4,866,899, 4,364,212 and 3,940,899 which require pop-up tabs extending from the center web of the stud to secure the wall board. The requirement of the pop-up tab requires additional labor and cost to manufacture the pop-up tabs by forming the pop-ups by hand or using a specially designed die. In comparison the present invention secures the wallboard directly to the flanges of the stud without the incorporation of pop-up tabs to secure the wall board. Furthermore, the incorporation of the pop-up tabs in U.S. Pat. Nos. 4,866,899, 4,364,212 and 3,940,899 compromises the strength of the stud.
In addition, U.S. Pat. Nos. 4,866,899, 4,364,212 and 3,940,899 do not provide a means or method for the construction of shaft wall with the ability to withstand seismic and wind sway movement.
U.S. Pat. No. 6,047,508 issued to Goodman is limited to the construction of a moveable wall panel with rigid frame. The invention does not disclose a means or method to construct a partition using a xe2x80x9cjxe2x80x9d-shaped stud that would withstand seismic forces. The invention claimed by Goodman has no ability to deflect after construction based upon its intended purpose to be a rigid pole which mates with another rigid pole. The xe2x80x9cG-shapedxe2x80x9d structure disclosed in the Goodman Patent (element 51) does not provide for movement of the attached wallboard, nor does it permit the user to attach opposing wallboard elements from one side. The G-shaped structure disclosed in Goodman performs as nothing more than a conventional stud requiring the attachment of opposing wallboard from each side of the structure based upon the dimensions disclosed therein.
The stud for construction of seismic and fire resistant shaft wall assemblies claimed herein permits construction of the shaft wall assembly strictly from within the shaft cavity as a result of the incongruence of the length of the anterior and posterior flanges which transversely depend from the vertical web of the stud thereby forming a generally J-shape cross-section. The incorporation of an elongated posterior flange in relation to the anterior flange allows the user to attach the interior shaft wallboard to the exterior side of the posterior flange from the anterior of the claimed stud. The incongruence between the posterior flange and anterior flange permits the user to insert a screw driver or screw gun into the channel formed between the flanges to securely attach the interior wall of the shaft wall assembly. If the posterior flange and anterior flange are substantially the same length, the user cannot secure the posterior flange to the wallboard which forms the exterior wall of the shaft cavity from the anterior side of the stud because the anterior flange obstructs the insertion of a nail gun or screw driver between the flanges to attach the interior wall board to the posterior flange. Consequently, if the anterior flange and posterior flange are substantially the same length, as found in the prior art, the interior shaft wallboard must be installed from both inside and outside the shaft cavity thereby requiring additional time and labor.
The incorporation of slots in the posterior flange through which the interior wall board is attached permits the wallboard to deflect horizontally as a result of physical forces such as earthquakes and wind sway. The ability of the wallboard to deflect horizontally during physical forces serves to protect the physical integrity of the wallboard against cracking. The existence of cracks in the wall compromises the wall assembly""s ability to resist the passage of fire, smoke and hot gases from the shaft cavity into the remainder of the building in the event of a fire. It is accordingly, an object of the invention to provide a stud for construction of a shaft wall assemblies which meets required safety standards for fire, wind loading and seismic forces set forth in current building codes, such as the Uniform Building Code.
It is an additional object to provide a stud for the construction of a cavity shaft wall which is relatively inexpensive, lightweight, and relatively easy to install. In comparison to the prior art, the claimed stud only requires four folds and less raw material for its construction which results in a cheaper selling price to consumer.
These and other objects and advantages of the invention will be more readily apparent when considered in relation to the preferred embodiments of the invention as set forth in the specification and shown in the drawings.